Intraluminal devices, such as guidewires and catheters, allow for a variety of disorders of the endovascular to be evaluated and treated without creating an open surgical field. Endovascular procedures typically include passing a guidewire through an access artery (e.g. brachial, femoral, radial) and to a vessel of interest within the vasculature. Once the guidewire is in place, a catheter is guided over the guidewire to perform an intraluminal procedure at the vessel of interest. An intraluminal procedure may require the introduction and exchange of several specialized catheters into the vasculature, which can lead to lengthy procedure times. As a result, changes have been made to the design of the catheters in order to improve their exchangeability and reduce procedure length.
A known catheter design for reducing procedure time is a rapid exchange configuration, which includes a guidewire lumen that only extends through the distal portion of the catheter. Prior to rapid exchange guidewire lumens, catheters often included an over-the-wire lumen that extended the entire length of the catheter device. Due to the long lumen, an over-the-wire catheter requires a guidewire more than twice the length of the catheter. This allows a physician to maintain a grip on the ex vivo portion of the guidewire when exchanging catheters. The long guidewire is cumbersome to handle, causes clutter, and often slows down an already lengthy procedure.
In contrast, a rapid exchange catheter has a guidewire lumen that only extends through the distal portion of the catheter. A typical known rapid exchange configuration includes a substantially L-shaped lumen that begins at a distal tip of the catheter and ends at a guidewire exit port, which is located on a side of the distal portion of the catheter and faces the vessel surface. In this configuration, the guidewire passes through the catheter shaft only for a segment of the length of the shaft, and the catheter can be moved along the guidewire in “monorail” fashion. Because the guidewire lumen is considerably shorter than the overall length of the catheter, a shorter guidewire can be used. For easy handling, the guidewire simply has to be long enough so that the length of the guidewire protruding from the patient is longer than the length of the guidewire lumen of the catheter. This ensures a portion of the guidewire is exposed at all times and may be grasped by the physician.
The current rapid exchange configuration suffers from some drawbacks, however. The rapid exchange design requires a portion of the guidewire to bend within the L-shaped guidewire lumen to exit the guidewire exit port located on the side of the catheter. In addition, the guidewire must bend again once out of the guidewire exit port in order to extend parallel to the proximal portion of the catheter. Because the guidewire exits the side of the catheter and then extends in parallel to the catheter, this configuration increases the vessel diameter requirements (i.e. the vessel must fit the combined diameters of the catheter and the guidewire).
In addition, the various bending of the guidewire may provide push issues or track issues with the catheter as it is being driven over the guidewire. A push issue arises when a proximal portion of a catheter is pushed further into the entry vessel and a distal end does not move the corresponding distance. A track issue arises when the proximal portion is torqued and the distal end does not rotate as expected. Pushing and tracking properly are crucial in negotiating the difficult curves or obstructions in the vasculature.
Thus, there is a need for a rapid exchange catheter with a low profile that reduces guidewire resistance.